Optical element driving device

ABSTRACT

An optical element driving device is provided, including a fixed part including a base; a movable part including a holder for carrying an optical element, a first driving mechanism configured to drive the holder to move along a first direction with respect to the base, and a position sensing assembly including a magnetic element and a magnetic field sensing element in corresponding positions and configured to sense the amount of displacement of the holder along the first direction with respect to the base, wherein the position sensing assembly and the magnetic element do not overlap with each other when viewed along a direction perpendicular to the first direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of application Ser. No. 15/668,182,filed on Aug. 3, 2017, which claims the benefit of U.S. ProvisionalApplication No. 62/421,592, filed on Nov. 14, 2016, and Taiwan PatentApplication No. 105124733, filed on Aug. 4, 2016, the entirety of whichare incorporated by reference herein.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to an optical element driving device, and inparticular to an optical element driving device that can move an opticalelement using electromagnetic force.

Description of the Related Art

Many handheld devices such as mobile phones and tablet PCs are equippedwith digital camera functionality as a basic requirement nowadays, andthis is made possible thanks to the miniaturization of optical elementdriving devices. In addition, handheld devices are usually equipped withother functions, such as autofocus (AF), optical image stabilization(OIS), and so on.

In a conventional optical element driving device including the autofocus(AF) function, in order to sense the position of the holder carrying theoptical element (e.g. a lens) on an image-capturing optical axis, acircuit substrate with a magnetic field sensor (e.g. a Hall sensor)thereon is provided adjacent to a lateral side of the holder to sensethe magnetic field strength change from a magnetic element (e.g. amagnet) mounted on the holder. However, the circuit substrate and themagnetic field sensor disposed on the lateral side of the holder willincrease the size of the optical element driving device, and thusadversely affect its prospects for miniaturization, and also limit thediameter of the lens.

In another conventional optical element driving device including theoptical image stabilization (OIS) function, in order to sense theposition of the holder carrying the lens on an image-capturing opticalaxis, a magnetic field sensor (e.g. a Hall sensor) is mounted on themovable part (e.g. the frame) of the optical element driving device tosense the magnetic field strength change from the magnetic element (e.g.a magnet) mounted on the holder. However, the magnetic field sensor willcause the weight of the movable part to increase, and thus more energyis required to move the movable part. In addition, a circuit thatcorresponds to the magnetic field sensor on the movable part is needed,making the finished product harder to manufacture.

Thus, to design an optical element driving device that can improve theaforementioned problems has become an important issue.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the invention provide an optical element driving device,including a fixed part, a movable part, a first driving mechanism, and aposition sensing assembly. The fixed part includes a base. The movablepart includes a holder for carrying an optical element. The firstdriving mechanism is configured to drive the holder to move along afirst direction with respect to the base. The position sensing assemblyincludes a magnetic element and a magnetic field sensing element incorresponding position and is configured to sense the amount ofdisplacement of the holder along the first direction with respect to thebase. The magnetic pole direction of the magnetic element is differentfrom the first direction.

In some embodiments, the magnetic field sensing element determines theamount of displacement of the holder with respect to the base by sensingchanges in the direction of the magnetic field from the magneticelement.

In some embodiments, the magnetic field sensing element is disposed onthe base to sense the amount of displacement of the holder along thefirst direction with respect to the base. The first direction isparallel to an optical axis of the optical element.

In some embodiments, the magnetic element and the magnetic field sensingelement do not overlap when viewed along the first direction.

In some embodiments, the first driving mechanism includes a firstdriving coil and a driving magnetic element in corresponding positions.The magnetic field sensing element and the magnetic element arepartially overlapping when viewed from a direction that is perpendicularto the first direction

In some embodiments, the base is substantially rectangular. The drivingmagnetic element is located on a side of the base, and the magneticelement is located at a corner of the base.

In some embodiments, the base is substantially rectangular. The drivingmagnetic element is located at a corner of the base, and the magneticelement is located on a side of the base.

In some embodiments, the first driving mechanism includes a firstdriving coil and a driving magnetic element in corresponding positions.The magnetic pole direction of the driving magnetic element is differentfrom that of the magnetic element.

In some embodiments, the optical element driving device further includesa second driving mechanism including a second driving coil and thedriving magnetic element in corresponding positions. The second drivingcoil is disposed on the fixed part. The driving magnetic element isdisposed on the movable part. The second driving mechanism is configuredto drive the movable part to move along a second direction with respectto the base, wherein the second direction is different from the firstdirection.

In some embodiments, the fixed part further includes a circuit substratedisposed on the base. The second driving coil and the magnetic fieldsensing element are disposed on the circuit substrate.

In some embodiments, the fixed part further includes an image sensingmodule including a circuit substrate and an image sensing element. Theimage sensing element and the magnetic field sensing element aredisposed on the circuit substrate.

In some embodiments, the first driving mechanism includes a firstdriving coil and a driving magnetic element in corresponding positions.The holder has a protrusion on the outer peripheral surface thereof. Thefirst driving coil is disposed on a side of the protrusion. Theprotrusion is located between the magnetic element and the magneticfield sensing element.

In some embodiments, the position sensing assembly further includes aplurality of magnetic elements and a plurality of magnetic field sensingelements in corresponding positions. The magnetic field sensing elementsare arranged in a second direction different from the first direction.The magnetic field sensing elements are respectively configured to sensethe amount of displacement of a plurality of portions of the holder inthe first direction with respect to the base.

In some embodiments, the magnetic field sensing element is a GiantMagneto Resistance (GMR) sensor or a Tunneling Magneto Resistance (TMR)sensor.

In some embodiments, the first driving mechanism further includes aplurality of driving magnetic elements. The driving magnetic elementsnear the magnetic element and the driving magnetic elements away fromthe magnetic element have different structure.

Embodiments of the invention also provide an optical element drivingdevice, including a fixed part, a movable part, a first drivingmechanism, and a position sensing assembly. The fixed part includes abase. The movable part includes a holder for carrying an opticalelement. The first driving mechanism includes a first driving coil and adriving magnetic element in corresponding positions and is configured todrive the holder to move along a first direction with respect to thebase. The position sensing assembly includes a magnetic element and amagnetic field sensing element in corresponding positions and isconfigured to sense the amount of displacement of the holder along thefirst direction with respect to the base. The magnetic pole direction ofthe magnetic element is different from the magnetic pole direction ofthe driving magnetic element.

In some embodiments, the magnetic pole direction of the driving magneticelement is different from the first direction.

Embodiments of the invention also provide an optical element drivingdevice, including a base, a holder, a driving mechanism, and a positionsensing assembly. The holder is configured to carry an optical element.The driving mechanism is configured to drive the holder to move along afirst direction with respect to the base. The position sensing assemblyincludes a magnetic element and a magnetic field sensing element incorresponding positions. The magnetic element is disposed on the holder.The magnetic field sensing element is disposed on the base andconfigured to sense the magnetic element's magnetic field strengthchanges perpendicular to an optical axis of the optical element todetermine the amount of displacement of the holder along the firstdirection with respect to the base. The first direction is parallel tothe optical axis.

In some embodiments, the magnetic field sensing element includes apackage body having a top surface and a mounting surface opposite toeach other, and the mounting surface is connected to the base. Themagnetic field sensing element is configured to sense the magneticelement's magnetic field strength changes parallel to the top surface.

In some embodiments, the magnetic element and the magnetic field sensingelement do not overlap when viewed along the first direction.

In order to illustrate the purposes, features, and advantages of theinvention, the preferred embodiments and drawings of the invention areshown in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is a partial exploded view of an optical element driving devicein accordance with some embodiments of the invention;

FIG. 2 is an exploded view of the optical element driving module in FIG.1;

FIG. 3 is a schematic view showing the direction of changes in themagnetic field strength detected by the magnetic field sensing elementin FIG. 2;

FIG. 4 is a schematic view showing the relative position of the magneticelement and the magnetic field sensing element of the position sensingassembly in accordance with some embodiments of the invention;

FIG. 5 is a partial exploded view of an optical element driving devicein accordance with some embodiments of the invention;

FIG. 6 is an exploded view of the optical element driving module in FIG.5;

FIG. 7 is a cross-sectional view take along the line A-A′ in FIG. 5;

FIG. 8 is a schematic view showing that the magnetic field sensingelement is disposed on the image sensing module in accordance with someembodiments;

FIG. 9 is a schematic view showing that the magnetic field sensingelement can sense changes in the direction of the magnetic field fromthe magnetic element;

FIGS. 10A and 10B are, respectively, schematic views showing therelative position of the driving magnetic elements, the magnetic elementand the magnetic field sensing element when viewed along the opticalaxis of the optical element in accordance with some embodiments;

FIGS. 11A to 11D are, respectively, schematic views showing variousmeans for reducing the magnetic interference between the drivingmagnetic elements and the magnetic element in accordance with someembodiments;

FIG. 12 is a schematic view showing that multiple magnetic field sensingelements are disposed on the fixed part to sense the tilt or rotation ofthe holder; and

FIGS. 13A and 13B are, respectively, schematic views showing therelative position of the magnetic field sensing elements and the movablepart when viewed along the optical axis of the optical element inaccordance with some embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The making and using of the embodiments of an optical element drivingdevice are discussed in detail below. It should be appreciated, however,that the embodiments provide many applicable inventive concepts that canbe embodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the embodiments, and do not limit the scope of the disclosure.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. It should be appreciated thateach term, which is defined in a commonly used dictionary, should beinterpreted as having a meaning conforming to the relative skills andthe background or the context of the present disclosure, and should notbe interpreted in an idealized or overly formal manner unless definedotherwise.

In addition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed. Variousfeatures may be arbitrarily drawn in different scales for the sake ofsimplicity and clarity. Furthermore, some elements not shown ordescribed in the embodiments have the forms known by persons skilled inthe field of the invention.

Referring to FIG. 1, an optical element driving device 1 according tosome embodiments may be provided, for example, inside an electronicdevice such as a camera, a mobile phone, or a tablet PC. The opticalelement driving device 1 includes an optical element driving module 10and an image sensing module 20. The optical element driving module 10 isused to carry an optical element including, for example, a lens,mirrors, and/or a light source. For ease of explanation, the carriedoptical element is only represented by a lens in the followingdescriptions. Moreover, the optical element driving module 10 can drivethe lens to move along its optical axis O (i.e. the Z-axis direction inthe figure) with respect to the image sensing module 20 positioned on aside of the optical element driving module 10, thereby achievingautofocus (AF). The image sensing module 20 includes a circuit substrate200 and an image sensing element 210 mounted on the circuit substrate200. The circuit substrate 200 may be a flexible printed circuit board(FPC) and the image sensing element 210 may be a charge-coupled device(CCD) or a complementary metal-oxide-semiconductor (CMOS) sensor.

Referring to FIG. 2, the optical element driving module 10 according tosome embodiments includes a top casing 11, a base 12, a holder 13, adriving mechanism 15, multiple elastic members 16A, 16B, and a positionsensing assembly 19.

The top casing 11 has a hollow cubic structure and can be combined withthe base 12 that is substantially rectangular for receiving otherparts/elements of the optical element driving module 10 as describedabove. The top casing 11 has an opening 11A through which the lens (notshown) in the optical element driving module 10 can capture light fromthe outside. The opening 11A and another opening 12A on the base 12correspond to each other and are located on the optical axis O of thelens. Accordingly, the lens and the image sensing element 210 of theimage sensing module 20 on a side (near the base 12) of the opticalelement driving module 10 can perform image focusing in the direction ofthe optical axis O.

The holder 13 has a through hole 13A for receiving the lens. Inaccordance with some embodiments, the through hole 13A forms a threadstructure corresponding to another thread structure on the periphery ofthe lens, such that the lens can be screwed into the through hole 13A.In accordance with some embodiments, the shape of the holder 13 isquadrilateral, octagonal, or other optional polygons.

The (electromagnetic) driving mechanism 15 includes a driving coil C1and multiple (e.g. four) driving magnetic elements M (e.g. magnets). Thedriving coil C1 is wound around the outer peripheral surface of theholder 13. In the embodiments of FIG. 2, the driving magnetic elements Mare trapezoidal (or triangular) and disposed at four inner corners ofthe top casing 11 to correspond to the driving coil C1. In someembodiments, the driving magnetic elements M are elongated and disposedon four inner sidewalls of the top casing 11.

With the above configuration, when a driving signal (e.g. current) froman external driving unit (not shown) is supplied to the driving coil C1,the driving coil C1 can act with the magnetic field from the drivingmagnetic elements M to generate an electromagnetic force to drive theholder 13 and the lens therein to move along the optical axis O (firstdirection) with respect to the base 12, thereby performing imagefocusing.

Moreover, the holder 13 may be disposed between the elastic members 16Aand 16B (for example, two metal sheets) comprising an elastic materialand movably suspended at the center of the optical element drivingmodule 10 by the elastic members 16A and 16B. For example, the outerperipheral portion and inner peripheral portion of the elastic member16A are respectively connected to the upper sides of the top casing 11and holder 13, and the outer peripheral portion and inner peripheralportion of the elastic member 16B are respectively connected to thelower sides of the base 12 and holder 13. Thus, the elastic members 16Aand 16B can provide a buffer capacity for the displacement of the holder13 along the optical axis O and avoid damage to the holder 13 and thelens therein.

Furthermore, in order to achieve the autofocus (AF) function of theoptical element driving module 10, the position sensing assembly 19includes a magnetic element 19A and a magnetic field sensing element 19Brespectively mounted on the holder 13 and the base 12 and correspondingto each other. The magnetic element 19A may be a magnet. The magneticfield sensing element 19B may be a Giant Magneto Resistance (GMR) sensoror a Tunneling Magneto Resistance (TMR) sensor that can be used todetect the magnetic field strength change caused by movement of themagnetic element 19A on the holder 13, thereby determining the amount ofdisplacement of the holder 13 and the lens therein along the opticalaxis O with respect to the base 12. In other words, when the holder 13moves back and forth along the optical axis O, the magnetic fieldsensing element 19B can detect the change in the magnetic field strength(i.e. the change in magnetic flux density) from the magnetic element19A, so as to determine the position of the holder 13 on the opticalaxis O.

In accordance with some embodiments, the magnetic field sensing element19B is a surface mount device (SMD) and includes a package body having atop surface 191 and a mounting surface 192 opposite to each other,wherein the mounting surface 192 is used to connect the base 20 (seeFIG. 4).

In the embodiments of FIG. 2, the magnetic field sensing element 19B maybe mounted on a circuit substrate (e.g. a FPC; not shown), and thecircuit substrate is affixed to the base 12. However, in someembodiments, electrical circuits may also be formed directly on thesurface of the base 12, and the magnetic field sensing element 19B ismounted on the base 12 and electrically connected to the electricalcircuits. Alternatively, the surface of the base 12 may form a recessfor receiving the magnetic field sensing element 19B.

In addition, the circuit substrate described above may electricallyconnect to the driving coil C1 on the holder 13 via the elastic members16A and/or 16B. Accordingly, the external driving unit (not shown) canfurther control the movement of the holder 13 along the optical axis Obased on the sensing result of the magnetic field sensing element 19B,thereby achieving autofocus (AF).

In the embodiments of FIG. 2, as the magnetic field sensing element 19Bfor sensing the position of the holder 13 on the optical axis O isdisposed on the base 12 or the circuit substrate on the base 12 ratherthan disposed on an additional circuit substrate provided on the lateralside of the holder 13, the miniaturization of the optical elementdriving device 1 can be implemented easily, or the diameter of the lenscan be increased.

Note that the magnetic field sensing element 19B using a TMR sensor or aTMR sensor also has the following advantages: The sensing sensitivity ofthe GMR sensor or TMR sensor is several times the sensing sensitivity ofthe traditional Hall sensor. In addition, the GMR sensor or TMR sensormay also sense or detect the magnetic element 19A's magnetic fieldstrength changes parallel to the top surface 191 of the magnetic fieldsensing element 19B (the double arrow A depicted in FIG. 3 representsthe direction of changes in the magnetic field strength that can bedetected by the magnetic field sensing element 19B), that is, the GMRsensor or TMR sensor can sense the magnetic element 19A's magnetic fieldstrength changes perpendicular to the optical axis O (see FIGS. 3 and4), thereby determining the amount of displacement of the holder 13along the optical axis O with respect to the base 12.

It should be appreciated that the direction of changes in the magneticfield strength detected by the magnetic field sensing element 19B isparallel to the top surface 191 of its package body (i.e. perpendicularto the optical axis O), and thus, although the magnetic element 19A onthe holder 13 and the magnetic field sensing element 19B are not alignedwell or not overlapped (FIG. 4) in the direction of the optical axis O(i.e. the Z-axis direction), the magnetic field sensing element 19B canstill detect the change in the magnetic field strength caused bymovement of the magnetic element 19A along the optical axis O, so as todetermine the amount of displacement of the magnetic element 19A and theholder 13 along the optical axis O with respect to the base 12. As aresult, not only the problem wherein the magnetic field sensing element19B may not precisely detect the changes in the magnetic field strengthfrom the magnetic element 19A caused by assembly tolerance can beavoided, also the height T of the optical element driving module 10 isreduced, thereby achieving thinner device.

Conversely, the direction of changes in the magnetic field strengthwhich can be detected by the traditional Hall sensor is perpendicular toits top surface, and thus the assembly tolerance between the traditionalHall effect sensor and the magnetic element 90 is strictly limited (i.e.the traditional Hall sensor and the magnetic element 90 can only bealigned with each other).

Next, referring to FIG. 5 which is a partial exploded view of an opticalelement driving device 1′ in accordance with other embodiments of theinvention. The optical element driving device 1′ differs from theoptical element driving device 1 of the above embodiments in that theoptical element driving module 10′ of the optical element driving device1′ also includes an optical image stabilization (OIS) mechanism whichmay drive a movable part and the lens to move on a plane (i.e. the XYplane in the figure) perpendicular to the optical axis O to carry outoptical shake compensation, so that the image quality can be improved.

Referring to FIG. 6 and FIG. 7, the optical element driving module 10′according to some embodiments includes a top casing 11, a base 12, aholder 13, a frame 14, a first driving mechanism 15, multiple elasticmembers 16A, 16B and 16C, a second driving mechanism 17, a circuitsubstrate 18, and a position sensing assembly 19. It should beunderstood that the top casing 11, base 12, circuit substrate 18,position sensing assembly 19 and the image sensing module 20 (FIG. 5)belong to a fixed part of the optical element driving device 1′, and thebase 12 and holder 13 belong to a movable part of the optical elementdriving device 1′ that can be driven by the first driving mechanism 15and second driving mechanism 17. The structure and function of theparts/elements of the optical element driving module 10′ will bedescribed in detail with reference to the accompanying drawings, and thevariations of some embodiments are discussed.

The top casing 11 and the base 12 may be combined with each other andused to receive other parts/elements of the optical element drivingmodule 10′ as described above. The top casing 11 has an opening 11Athrough which the lens (not shown) in the optical element driving module10′ can capture light from the outside. The opening 11A and anotheropening 12A on the base 12 correspond to each other and are located onthe optical axis O of the lens. Accordingly, the lens and the imagesensing element 210 of the image sensing module 20 on a side (near thebase 12) of the optical element driving module 10′ can perform imagefocusing in the direction of the optical axis O.

The holder 13 has a through hole 13A for receiving the lens. Inaccordance with some embodiments, the through hole 13A forms a threadstructure corresponding to another thread structure on the periphery ofthe lens, such that the lens can be screwed into the through hole 13A.In accordance with some embodiments, the shape of the holder 13 isquadrilateral, octagonal, or other optional polygons. The frame 14 has ahollow annular structure and the holder 13 is disposed in the frame 14.In accordance with some embodiments, the shape of the frame 14 isquadrilateral, octagonal, or other optional polygons.

The first (electromagnetic) driving mechanism 15 includes a driving coilC1 (first driving coil) and multiple (e.g. four) driving magneticelements M (e.g. magnets). The driving coil C1 is wound around the outerperipheral surface of the holder 13. In the embodiments of FIG. 6, thedriving magnetic elements M are elongated and disposed on four sides ofthe octagonal frame 14 to correspond to the driving coil C1. Morespecifically, two driving magnetic elements M are arranged parallel tothe X-axis direction in the figure, and the other two driving magneticelements M are arranged parallel to the Y-axis direction in the figure.In accordance with some embodiments, the driving magnetic elements M maybe triangular or trapezoidal and disposed at four corners of the frame14. In accordance with some embodiments, the positions of the drivingcoil C1 and the driving magnetic elements M may also be exchanged, thatis the driving coil C1 may be disposed on the frame 14 and the drivingmagnetic elements M may be disposed on the holder 13.

With the above configuration, when a driving signal (e.g. current) froman external driving unit (not shown) is supplied to the driving coil C1,the driving coil C1 can act with the magnetic field from the drivingmagnetic elements M to generate an electromagnetic force to drive theholder 13 and the lens therein to move along the optical axis O (firstdirection) with respect to the frame 14 and the base 12, therebyperforming image focusing.

Moreover, the holder 13 may be disposed between the elastic members 16Aand 16B (for example, two metal sheets) comprising an elastic materialand movably suspended at the center of the frame 14 by the elasticmembers 16A and 16B. For example, the outer peripheral portions of theelastic members 16A and 16B are respectively connected to the upper andlower sides of the frame 14, and the inner peripheral portions of theelastic members 16A and 16B are respectively connected to the upper andlower sides of the holder 13. Thus, the elastic members 16A and 16B canprovide a buffer capacity for the displacement of the holder 13 alongthe optical axis O and avoid damage to the holder 13 and the lenstherein.

The circuit substrate 18 may be a FPC and fixedly disposed on the base12. Also, the circuit substrate 18 electrically connects to an externaldriving unit (not shown) outside the optical element driving module 10′and can be used to perform optical image stabilization (OIS) andautofocus (AF) functionality which will be further described later.

Multiple (e.g. four) elastic members 16C may be flexible metal wires.One end of each elastic member 16C is connected to the circuit substrate18, and the other end is connected to the elastic member 16A whichconnects to the upper side of the frame 14. In this way, the elasticmembers 16C can suspend the frame 14 and the holder 13 and lens thereinabove the base 12.

The second (electromagnetic) driving mechanism 17 includes a drivingboard C2 and the driving magnetic elements M described above (that is,the driving magnetic elements M are shared components of the firstdriving mechanism 15 and the second driving mechanism 17). The drivingboard C2 may be a FPC and fixed disposed on the circuit substrate 18 andelectrically connected thereto. In the embodiments of FIG. 6, thedriving board C2 is rectangular and has multiple (e.g. four) drivingcoils (second driving coils) therein. The positions of the four seconddriving coils respectively correspond to the positions of the fourdriving magnetic elements M, wherein two second driving coils located onopposite sides of the driving board C2 may be parallel to X-axisdirection, and two second driving coils located on other opposite sidesof the driving board C2 may be parallel to Y-axis direction.

Moreover, two magnetic field sensing elements 18A are respectivelymounted on two sides of the circuit substrate 18 extending in the X-axisand Y-axis directions. The magnetic field sensing elements 18A may beHall sensors, MR sensors, or Fluxgate sensors, and can be used to detectthe magnetic field strength change caused by movement of the drivingmagnetic elements M on the frame 14, thereby determining the positionoffset amount of the frame 14 and the holder 13 and lens therein withrespect to the base 12 in the X-axis and Y-axis directions. Furthermore,when a driving signal (e.g. current) from an external driving unit (notshown) is supplied to the second driving coils of the driving board C2through the circuit substrate 18, an electromagnetic force generatedbetween the second driving coils and the driving magnetic elements M candrive the frame 14 and the holder 13 therein to move along at least one(second) direction (the X-axis direction and/or the Y-axis direction)perpendicular to the optical axis O to compensate for the positionoffset described above. As a result, the OIS function is achieved.

In the embodiments of FIGS. 6 and 7, the position sensing assembly 19includes a magnetic element 19A and a magnetic field sensing element19B. The magnetic element 19A may be a magnet and fixedly disposed in arecess 13B on the outer peripheral surface of the holder 13 (but theinvention is not limited thereto, and the magnetic element 19A may alsobe disposed on the frame 14 in some embodiments). The magnetic fieldsensing element 19B is disposed on the circuit substrate 18 andelectrically connected thereto. The position of the magnetic fieldsensing element 19B corresponds to position of the magnetic element 19A.In accordance with some embodiments, the holder 13 has a protrusion 13Con the outer peripheral surface thereof. The driving coil C1 is disposedon a side (e.g. lower side) of the protrusion 13C, and the protrusion13C is located between the magnetic element 19A and the magnetic fieldsensing element 19B (see FIG. 7).

In accordance with some embodiments, the magnetic field sensing element19B is a GMR sensor or a TMR sensor and can be used to detect themagnetic field strength change caused by movement of the magneticelement 19A on the holder 13, thereby determining the amount ofdisplacement of the holder 13 and the lens therein along the opticalaxis O with respect to the base 12. In other words, when the holder 13moves back and forth along the optical axis O, the magnetic fieldsensing element 19B can detect the change in the magnetic field strength(i.e. the change in magnetic flux density) from the magnetic element19A, so as to determine the position of the holder 13 on the opticalaxis O.

Although not shown in the drawings, the circuit substrate 18 mayelectrically connect to the driving coil C1 on the holder 13 via theelastic members 16C and 16A in some embodiments. Accordingly, theexternal driving unit (not shown) can further control the movement ofthe holder 13 along the optical axis O based on the sensing result ofthe magnetic field sensing element 19B, thereby achieving autofocus(AF).

It should be appreciated that, in the embodiments of FIGS. 6 and 7, themagnetic field sensing element 19B for sensing the position of theholder 13 carrying the lens on the optical axis O is disposed on thecircuit substrate 18 (fixed part), so that the weight of movable part ofthe optical element driving device 1′ and the consumption of drivingenergy can be reduced (compared to conventional technology), improvingthe performance of the optical element driving device 1′. Moreover,since the magnetic field sensing element 19B is directly electricallyconnected to the circuit substrate 18, it is not necessary to provide acorresponding circuit on the movable part. As a result, the wiringlayout is simplified and the manufacturing difficulty of the opticalelement driving device 1′ is reduced.

In accordance with some embodiments, the magnetic field sensing element19B may also be disposed on the circuit substrate 200 of the imagesensing module 20 and electrically connected thereto (see FIG. 8), toreduce the weight of movable part of the optical element driving device1′, reduce the consumption of driving energy and simplify the wiringlayout as described above.

Furthermore, the magnetic field sensing element 19B using a TMR sensoror a TMR sensor also has the following advantages: The sensingsensitivity of the GMR sensor or TMR sensor is several times the sensingsensitivity of the traditional Hall sensor. In addition, the GMR sensoror TMR sensor may also detect the movement of the holder 13 with respectto the base 12 by sensing the change in the magnetic field directionfrom the magnetic element 19A.

As shown in FIG. 9, if the magnetic element 19A on the holder 13 and themagnetic field sensing element 19B are not aligned well or notoverlapped in the direction of the optical axis O (i.e. the Z-axisdirection), the magnetic field sensing element 19B may also detect thechange in the magnetic field direction (for example, from the magneticline F1 to the magnetic line F2) caused by movement (for example, fromthe position P1 to the position P2) of the magnetic element 19A alongthe optical axis O, so as to determine the amount of displacement of themagnetic element 19A and the holder 13 along the optical axis O withrespect to the base 12. Therefore, when the magnetic element 19A on theholder 13 and the magnetic field sensing element 19B are not alignedwell or not overlapped in the direction of the optical axis O, themagnetic field sensing element 19B can detect the changes in thestrength and direction of the magnetic field from the magnetic element19A, so that the sensing accuracy is increased.

Moreover, as shown in FIG. 7, when the magnetic element 19A on theholder 13 and the magnetic field sensing element 19B are not overlappedin the direction of the optical axis O, the height T of the opticalelement driving module 10′ is also reduced and thus the miniaturizationis achieved.

FIGS. 10A and 10B are, respectively, schematic views showing therelative position of the driving magnetic elements M, the magneticelement 19A and the magnetic field sensing element 19B when viewed alongthe optical axis O of the lens in accordance with some embodiments. Itshould be first understood that the driving magnetic elements M and themagnetic element 19A are partially overlapped (in order to make thedevice thinner) when viewed from a direction that is perpendicular tothe optical axis O and thus magnetic interference between the drivingmagnetic elements M and the magnetic element 19A is likely to occur,causing the focus speed and accuracy of the optical element drivingmodule 10′ to be reduced and the sensing accuracy of the magnetic fieldsensing element 19B to be adversely affected. Therefore, the drivingmagnetic elements M and the magnetic element 19A are preferably arrangedso as to not overlap in the direction of the optical axis O.

As shown in FIG. 10A, when viewed along the optical axis O, multipleelongated driving magnetic elements M may be arranged on four sides ofthe substantially rectangular base 12 (not shown) and the magneticelement 19A and magnetic field sensing element 19B may be arranged at acorner of the base 12 (wherein the magnetic element 19A is closer to thelens than the magnetic field sensing element 19B, and they do notoverlap). As shown in FIG. 10B, when viewed along the optical axis O,multiple trapezoidal driving magnetic elements M may be arranged at fourcorners of the substantially rectangular base 12 (not shown) and themagnetic element 19A and magnetic field sensing element 19B may bearranged on a side of the base 12.

Additionally, in order to further reduce the magnetic interferencebetween the driving magnetic elements M and the magnetic element 19A,embodiments of the invention also provide various technical means asdescribed below.

As shown in FIG. 11A, a magnetic isolation member (or shield) N may beprovided between the adjacent driving magnetic element M and themagnetic element 19A in some embodiments. The magnetic isolation memberN may comprise a magnetic conductive material (such as nickel-ironalloy) and can be used to avoid leakage of the magnetic lines of thedriving magnetic element M and the magnetic element 19A.

As shown in FIG. 11B, the length L1 of the driving magnetic elements Mnear the magnetic element 19A may be less than the length L2 of thedriving magnetic elements M away from the magnetic element 19A (i.e.different structure) in some embodiments. Alternatively, the drivingmagnetic elements M all have the same length, but the driving magneticelements M near the magnetic element 19A each have a non-magnetic regionU (depicted in dashed lines), i.e. not magnetized. As shown in FIG. 11C,the driving magnetic elements M all have the same length, but thedriving magnetic elements M near the magnetic element 19A each have anotch R (i.e. different structure) in some embodiments.

As shown in FIG. 11D, the magnetic pole direction (N-S) of the drivingmagnetic elements M may also be different from the magnetic poledirection (N-S) of the magnetic element 19A in some embodiments, so asto reduce the magnetic interference between the driving magneticelements M and the magnetic element 19A. For example, the magnetic poledirection (N-S) of the magnetic element 19A may be parallel to theoptical axis O and the magnetic pole direction (N-S) of the drivingmagnetic elements M may be perpendicular to the optical axis O.Alternatively, the magnetic pole direction (N-S) of the magnetic element19A may be perpendicular to the optical axis O and the magnetic poledirection (N-S) of the driving magnetic elements M may be parallel tothe optical axis O. In accordance with some embodiments, the magneticpole direction (N-S) of the magnetic element 19A may also be inclinedwith respect to the optical axis O. In addition, the driving magneticelements M and/or the magnetic element 19A may also be multipole magnetsso that the magnetic interference therebetween can be reduced further.

Next, referring to FIG. 12 which is a schematic view showing thatmultiple magnetic field sensing elements 19B are disposed on the fixedpart to sense the tilt or rotation of the holder 13. It should be firstunderstood that the magnetic element 19A (not shown in FIG. 12) of theposition sensing assembly 19 is not provided at the center of gravity ofthe holder 13, so that the change in the strength or direction of themagnetic field of the magnetic element 19A detected by the singlemagnetic field sensing element 19B does not necessarily indicate theoverall movement of the holder 13 but may only indicate the holder 13has tilted or rotated (for example, the holder 13 may be tilted withrespect to a horizontal plane H perpendicular to the optical axis O dueto shock as shown in FIG. 12).

In order to overcome this noise interference problem and improve thesensing accuracy, multiple magnetic field sensing elements 19B may bedisposed on the fixed part (e.g. the circuit substrate 18) of theoptical element driving device 1′ to respectively sense the amount ofdisplacement of multiple portions (provided with multiple magneticelements 19A corresponding to the magnetic field sensing elements 19B)of the holder 13 in the same direction (e.g. the direction of opticalaxis O) with respect to the base 12 (see FIG. 12), and then theinformation sensed by the magnetic field sensing elements 19B iscalculated and analyzed to determine the real movement of the holder 13.

In accordance with some embodiments (as shown in FIG. 13A), multiple(e.g. two) magnetic field sensing elements 19B may be disposed at twoopposite corners of the circuit substrate 18 (corresponding to twoopposite corners of the frame 14) and arranged in a direction notparallel to the X-axis direction in the figure, for example. Inaccordance with some embodiments (as shown in FIG. 13A), multiple (e.g.two) magnetic field sensing elements 19B may be disposed at two adjacent(i.e. on the same side) corners of the circuit substrate 18(corresponding to two adjacent corners of the frame 14) and arranged ina direction parallel to the X-axis direction in the figure, for example.

In accordance with some embodiments, the above magnetic field sensingelements 19B may each include multiple magnetic field sensing subunits(e.g. GMR sensors or TMR sensors) in its package. The magnetic fieldsensing subunits can be used to sense the amount of displacement of theholder 13 in different directions (e.g. at least two of the X-axisdirection, the Y-axis direction and the Z-axis direction). Accordingly,the magnetic field sensing elements 19B may be substituted for themagnetic field sensing elements 18A on the circuit substrate 18 and thenumber of elements in the optical element driving module 10′ is reduced.

Although embodiments of the present disclosure and their advantages havebeen described in detail, it should be understood that various changes,substitutions and alterations can be made herein without departing fromthe spirit and scope of the disclosure as defined by the appendedclaims. For example, it will be readily understood by those skilled inthe art that many of the features, functions, processes, and materialsdescribed herein may be varied while remaining within the scope of thepresent disclosure. Moreover, the scope of the present application isnot intended to be limited to the particular embodiments of the process,machine, manufacture, composition of matter, means, methods and stepsdescribed in the specification. As one of ordinary skill in the art willreadily appreciate from the disclosure of the present disclosure,processes, machines, manufacture, compositions of matter, means,methods, or steps, presently existing or later to be developed, thatperform substantially the same function or achieve substantially thesame result as the corresponding embodiments described herein may beutilized according to the present disclosure. Accordingly, the appendedclaims are intended to include within their scope such processes,machines, manufacture, compositions of matter, means, methods, or steps.In addition, each claim constitutes a separate embodiment, and thecombination of various claims and embodiments are within the scope ofthe disclosure.

What is claimed is:
 1. An optical element driving device, comprising: afixed part including a base; a movable part including a holder forcarrying an optical element; a first driving mechanism configured todrive the holder to move along a first direction with respect to thebase; and a position sensing assembly including a magnetic element and amagnetic field sensing element in corresponding positions and configuredto sense the amount of displacement of the holder along the firstdirection with respect to the base, wherein a second direction isperpendicular to the first direction, and a third direction isperpendicular to the first direction and the second direction, themagnetic field sensing element and the magnetic element are arranged inthe second direction when viewed from the first direction, and themagnetic field sensing element does not overlap the magnetic elementwhen viewed along the second direction and the third direction.
 2. Theoptical element driving device as claimed in claim 1, wherein the firstdriving mechanism includes a first driving coil and a driving magneticelement in corresponding positions, the magnetic element has twomagnetic poles aligned in a magnetic pole direction, and the magneticpole direction of the driving magnetic element is different from that ofthe magnetic element.
 3. The optical element driving device as claimedin claim 1, wherein the fixed part further includes an image sensingmodule including a circuit substrate and an image sensing element, andthe image sensing element and the magnetic field sensing element aredisposed on the circuit substrate.
 4. The optical element driving deviceas claimed in claim 1, wherein the first driving mechanism includes afirst driving coil and a driving magnetic element in correspondingpositions, and wherein the holder has a protrusion on an outerperipheral surface of the holder, the first driving coil is disposed ona side of the protrusion, and the protrusion is located between themagnetic element and the magnetic field sensing element.
 5. The opticalelement driving device as claimed in claim 1, wherein the magnetic fieldsensing element is a Giant Magneto Resistance sensor or a TunnelingMagneto Resistance sensor.
 6. The optical element driving device asclaimed in claim 1, wherein the magnetic field sensing elementdetermines the amount of displacement of the holder with respect to thebase by sensing changes in the direction of the magnetic field from themagnetic element.
 7. The optical element driving device as claimed inclaim 6, wherein the magnetic element and the magnetic field sensingelement do not overlap when viewed along the first direction.
 8. Theoptical element driving device as claimed in claim 6, wherein theposition sensing assembly further includes a plurality of magneticelements and a plurality of magnetic field sensing elements incorresponding positions, wherein the magnetic field sensing elements arearranged in a second direction that is different from the firstdirection, and the magnetic field sensing elements are respectivelyconfigured to sense an amount of displacement of a plurality of portionsof the holder in the first direction with respect to the base.
 9. Theoptical element driving device as claimed in claim 6, wherein the firstdriving mechanism includes a first driving coil and a driving magneticelement in corresponding positions, and the magnetic field sensingelement and the magnetic element are partially overlapping when viewedfrom a direction that is perpendicular to the first direction.
 10. Theoptical element driving device as claimed in claim 9, wherein the baseis rectangular, the driving magnetic element is located on a side of thebase, and the magnetic element is located at a corner of the base. 11.The optical element driving device as claimed in claim 9, wherein thebase is rectangular, the driving magnetic element is located at a cornerof the base, and the magnetic element is located on a side of the base.12. The optical element driving device as claimed in claim 9, whereinthe first driving mechanism further includes a plurality of drivingmagnetic elements, and the driving magnetic elements comprises a firstdriving magnetic element and a second driving magnetic element havingdifferent shapes, and a distance between the first driving magneticelement and the magnetic element is different from a distance betweenthe second driving magnetic element and the magnetic element.
 13. Theoptical element driving device as claimed in claim 6, wherein themagnetic field sensing element is disposed on the base to sense theamount of displacement of the holder along the first direction withrespect to the base, and the first direction is parallel to an opticalaxis of the optical element.
 14. The optical element driving device asclaimed in claim 13, wherein the first driving mechanism includes afirst driving coil and a driving magnetic element, the optical elementdriving device further comprises a second driving mechanism including asecond driving coil and the driving magnetic element in correspondingpositions, wherein the second driving coil is disposed on the fixedpart, the driving magnetic element is disposed on the movable part, andthe second driving mechanism is configured to drive the movable part tomove along a second direction with respect to the base, wherein thesecond direction is different from the first direction.
 15. The opticalelement driving device as claimed in claim 14, wherein the fixed partfurther includes a circuit substrate disposed on the base, and thesecond driving coil and the magnetic field sensing element are disposedon the circuit substrate.
 16. An optical element driving device,comprising: a fixed part including a base; a movable part including aholder for carrying an optical element; a first driving mechanismincluding a first driving coil and a driving magnetic element incorresponding positions and configured to drive the holder to move alonga first direction with respect to the base; and a position sensingassembly including a magnetic element and a magnetic field sensingelement in corresponding positions and configured to sense the amount ofdisplacement of the holder along the first direction with respect to thebase, wherein a second direction is perpendicular to the firstdirection, and a third direction is perpendicular to the first directionand the second direction, the magnetic field sensing element and themagnetic element are arranged in the second direction when viewed fromthe first direction the magnetic field sensing element does not overlapthe magnetic element when viewed along the second direction and thethird direction.
 17. The optical element driving device as claimed inclaim 16, wherein the magnetic element has two magnetic poles aligned ina magnetic pole direction, the magnetic pole direction of the drivingmagnetic element is different from the first direction.
 18. The opticalelement driving device as claimed in claim 16, wherein the magneticelement is disposed on the holder, and the magnetic field sensingelement is disposed on the base.
 19. The optical element driving deviceas claimed in claim 18, wherein the magnetic field sensing elementincludes a package body having a top surface and a mounting surfaceopposite to each other, and the mounting surface is connected to thebase, wherein the magnetic field sensing element is configured to sensethe magnetic element's magnetic field strength changes parallel to thetop surface.
 20. The optical element driving device as claimed in claim18, wherein the magnetic element and the magnetic field sensing elementdo not overlap when viewed along the first direction.